1. Field of the Invention
The present invention relates to an ink jet recording process and an apparatus therefor, in which a color recording is carried out by ejecting various color inks from each of a plurality of orifices corresponding to each of the various color inks.
2. Description of the Prior Art
The ink jet recording process is a recording process which possesses the following various advantages.
(1) Plane paper can be used for the process. PA1 (2) High-speed printing can be carried out by the process. PA1 (3) Little noise occurs upon printing. PA1 (4) The apparatus can be compacted. PA1 (5) Maintenance of an apparatus is easily carried out. PA1 (6) Multi-color printing is easily carried out. PA1 L.sub.ohc /L.sub.hcn =k (k is a constant to be unequivocally determined by the type of an ink to be used.)
Since the ink jet recording process possesses various advantages as described above, various types are proposed.
While the ink jet recording process can easily, in principle, carry out multi-color printing and produce colored printed letters having excellent quality in comparison to the other recording processes, the ink jet recording process is behind in practical use compared to the other recording process.
The causes of the above-mentioned situation are as follows. In the conventional process using electromechanical conversion elements such as piezo-elements and the like, the conventional process is unable to carry out multi-color printing having at least two colors or full-color printing while keeping high quality and high resolution of printed letters at high speed, since a recording head for printing can not be constructed compactly and the ejecting orifices can not be disposed in high density.
Recently, an ink jet recording process based on a quite different principle for forming flying droplets has been disclosed in DOLS 2843064.
In the ink jet recording process disclosed in the above-mentioned Gazette, a recording head can be very compactly prepared and the ejecting orifices disposed in high density, therefore the process possesses the advantages that printing can produce printed letters having high quality and high resolution at high speed, and the like.
Referring to FIG. 1, there is described an embodiment of a recording head 101 to be used in such a recording process.
An ink jet recording head shown in FIG. 1 is provided with plural orifices 106 (in FIG. 1, five orifices are shown) for ejecting an ink as droplets on a plane where the ink is ejected, a common ink chamber 108 which is disposed in parallel with the ink-ejecting plane, and a number of liquid chambers 104 through which each orifice is in communication with the common ink chamber 108.
In FIG. 1, the five ejecting orifices 106 (106-1 to -5), five liquid chambers (104-1 to -5) which each one of the chambers is in communication with each ejecting orifice, and the common ink chamber 108 which is communication with each one of liquid chambers 104 are formed by joining a substrate 102 to a cover 103 having grooves for forming liquid chambers and a concavity for forming the common ink chamber as shown in FIG. 1.
Heaters 105 are formed on the substrate 102 as means for generating heat energy corresponding to a printing signal by microfabrication such as thin-film forming process including sputtering process, vacuum deposition process, and the like, etching process, and the like. An ink which is ejected from the orifices 106 in form of droplets is introduced into the common ink chamber 108 through the ink supply tubes 107-1 and -2, and supplied to each one of liquid chambers 104. Bubbles are generated in the ink by heat energy applied from the heaters 105 to the ink supplied into each one of liquid chambers 104, then the ink is ejected in form of droplets from desired orifices 106 by being subjected to sudden pressure change resulting from the bubbles. One of the ink supply tubes 107-1 and -2 may be used for taking out bubbles from the ink.
In an ink jet recording process using the recording head shown in FIG. 1, it is easier in comparison with the case of the above-mentioned conventional process to embody an apparatus for multi-color or full-color printing with the above-mentioned high printing characteristics. However, there remain some points to be improved for enhancement of quality of the printed letters at high speed. Further, since each one of the various inks possesses different characteristics in the case of multi-color or full-color printing, it is desired to develop a recording head which possesses characteristics and structure which are adaptable so as to meet characteristics of all the inks used.